Pyrene derivative, organic light-emitting medium, and organic electroluminescent element containing pyrene derivative or organic light-emitting medium

ABSTRACT

An organic light-emitting medium including a pyrene derivative represented by the following formula (1) and a phenyl-substituted anthracene derivative represented by the following formula (2): 
     
       
         
         
             
             
         
       
     
     wherein Ar 1  to Ar 4  are independently a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms or a substituted or unsubstituted heteroaryl group having 5 to 20 ring atoms.

TECHNICAL FIELD

The invention relates to a pyrene derivative, an organic light-emittingmedium and an organic electroluminescence medium containing them.

BACKGROUND ART

An organic electroluminescence (EL) device using an organic substance isa promising solid-state emitting type inexpensive and large full-colordisplay device, and has been extensively developed. In general, anorganic EL device includes an emitting layer and a pair of opposingelectrodes holding the emitting layer therebetween. When an electricfield is applied between the electrodes, electrons are injected from thecathode and holes are injected from the anode. The electrons recombinewith the holes in the emitting layer to produce an excited state, andenergy is emitted as light when the excited state returns to the groundstate.

With an improvement in technology of prolonging the lifetime, an organicEL device of recent years are being applied to a full-color display suchas a mobile phone or a TV, and the performance of an organic EL devicehas been gradually improved with improvements in emitting materials foran organic EL device.

For example, in Patent Documents 1 to 3, a combination of an anthracenehost with a specific structure and a diaminopyrene dopant is disclosed.However, a further improvement in luminous properties (luminousefficiency, lifetime or the like) has been desired.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: WO2004/018587-   Patent Document 2: JP-A-2004-204238-   Patent Document 3: WO2005/108348

The invention has been made to solve the above-mentioned subject. Anobject of the invention is to provide a highly efficient and long-livedorganic EL device.

The inventors have found that an organic light-emitting medium obtainedby using a pyrene derivative having a specific structure at a specificposition and a phenyl-substituted anthracene derivative has a highluminous efficiency and has a long life. The inventors have also foundthat an organic electroluminescence device using an organic thin filmcomprising the organic light-emitting medium as an emitting layer has ahigh luminous efficiency and has a long life. The invention has beenmade based on this finding.

According to the invention, the following organic light-emitting medium,organic thin film and organic electroluminescence device are provided.

1. An organic light-emitting medium comprising a pyrene derivativerepresented by the following formula (1) and a phenyl-substitutedanthracene derivative represented by the following formula (2):

wherein

Ar¹ to Ar⁴ are independently a substituted or unsubstituted aryl grouphaving 6 to 30 carbon atoms that form a ring (hereinafter referred to as“ring carbon atoms”), or a substituted or unsubstituted heteroaryl grouphaving 5 to 20 atoms that form a ring (hereinafter referred to as “ringatoms”),

X¹ to X⁸ are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asilyl group which is substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms and/or a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms, or which is unsubstituted,a cyano group, a substituted or unsubstituted alkoxy group having 1 to20 carbon atoms, a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, a halogen atom, or a substituted orunsubstituted halogenated alkyl group having 1 to 20 carbon atoms,

R¹ to R⁸ are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asilyl group which is substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms or a substituted or unsubstituted arylgroup having 6 to 18 ring carbon atoms, or which is unsubstituted, acyano group, a substituted or unsubstituted alkoxy group having 1 to 20carbon atoms, a substituted or unsubstituted aryloxy group having 6 to30 ring carbon atoms, or a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, and

R¹ and R², R² and R³, R³ and R⁴, R⁵ and R⁶, R⁶ and R⁷, and R⁷ and R⁸ maybe bonded to each other to form a substituted or unsubstitutedhydrocarbon ring or a substituted or unsubstituted heterocyclic ring,

wherein

Ar¹¹ is a substituted or unsubstituted arylene group having 6 to 30 ringcarbon atoms or a substituted or unsubstituted heteroarylene grouphaving 5 to 20 ring atoms,

m is an integer of 0 to 3, provided that Ar¹¹ is a single bond when m is0,

Ar¹² is a substituted or unsubstituted aryl group having 6 to 30 ringcarbon atoms or a substituted or unsubstituted heteroaryl group having 5to 20 ring atoms,

n is an integer of 1 to 3, and

when m or n is 2 or more, plural Ar¹¹s and Ar¹²s may be the same ordifferent.

2. The organic light-emitting medium according to 1, wherein X¹ to X⁸are a hydrogen atom.3. The organic light-emitting medium according to 1, wherein X² and X⁶are a substituted or unsubstituted aryl group having 6 to 30 ring carbonatoms, a substituted or unsubstituted alkyl group having 1 to 20 carbonatoms or a substituted or unsubstituted cycloalkyl group having 3 to 20ring carbon atoms, and X¹, X³ to X⁵, X⁷ and X⁸ are a hydrogen atom.4. The organic light-emitting medium according to any one of 1 to 3,wherein Ar³ and Ar⁴ is a substituted or unsubstituted aryl group having6 to 30 ring carbon atoms.5. The organic light-emitting medium according to any of 1 to 4, whereinR³ and R⁷, or R² and R⁶ are a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms.6. The organic light-emitting medium according to 4 or 5, wherein Ar³and Ar⁴ are a substituted or unsubstituted phenyl group.7. The organic light-emitting medium according to 5 or 6, wherein R³ andR⁷, or R² and R⁶ are a substituted or unsubstituted phenyl group.8. The organic light-emitting medium according to any of 1 to 7, whereinm is 1 and n is 1.9. The organic light-emitting medium according to any of 1 to 7, whereinm is 0 and n is 1.10. The organic light-emitting medium according to 8, wherein Ar¹¹ is asubstituted or unsubstituted arylene group having 6 to 18 ring carbonatoms or a substituted or unsubstituted heteroarylene group having 5 to20 ring atoms, Ar¹² is a substituted or unsubstituted aryl group having6 to 18 ring carbon atoms or a substituted or unsubstituted heteroarylgroup having 5 to 20 ring atoms.11. The organic light-emitting medium according to 9, wherein Ar¹² is asubstituted or unsubstituted aryl group having 6 to 18 ring carbon atomsor a substituted or unsubstituted heteroaryl group having 5 to 20 ringatoms.12. The organic light-emitting device according to 10, wherein Ar¹¹ is asubstituted or unsubstituted phenylene group or a substituted orunsubstituted naphthalenylene group.13. The organic light-emitting medium according to 11, wherein Ar¹² is asubstituted or unsubstituted naphthyl group, a substituted orunsubstituted benzanthracenyl group, a substituted or unsubstitutedbenzphenanthrenyl group, a substituted or unsubstituted phenanthrylgroup or a substituted or unsubstituted dibenzofuranyl group.14. The organic light-emitting medium according to 12, wherein Ar¹¹ is asubstituted or unsubstituted phenylene group and Ar¹² is a substitutedor unsubstituted naphthyl group.15. A pyrene derivative represented by the following formula (10):

wherein

Ar¹ to Ar⁴ are independently a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, or a substituted or unsubstitutedheteroaryl group having 5 to 20 ring atoms,

X¹ to X⁸ are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asilyl group which is substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms and/or a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms, or which is unsubstituted,a cyano group, a substituted or unsubstituted alkoxy group having 1 to20 carbon atoms, a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atoms, a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, a halogen atom, or a substituted orunsubstituted halogenated alkyl group having 1 to 20 carbon atoms,

R¹¹, R¹², R¹⁴ to R¹⁶ and R¹⁸ are independently a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, a silyl group which is substituted by a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms and/or asubstituted or unsubstituted aryl group having 6 to 18 ring carbonatoms, or which is unsubstituted or a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms.

16. An organic electroluminescence medium comprising an anode and acathode, and one or more organic thin film layers including an emittinglayer between the anode and the cathode;

the emitting layer comprising the organic light-emitting deviceaccording to any of 1 to 14 or the pyrene derivative according to 15.

According to the invention, an organic light-emitting medium, an organicthin film and an organic EL device with a high efficiency and long lifecan be provided.

MODE FOR CARRYING OUT THE INVENTION

The organic emission medium and the organic EL device of the inventionwill be described in detail hereinbelow.

I. Organic Emission Medium

The organic emission medium of the invention is characterized in that itcomprises a pyrene derivative represented by the following formula (1)and a phenyl-substituted anthracene derivative represented by thefollowing formula (2).

Here, the pyrene derivative represented by the formula (1) functions asa doping material (dopant), and the phenyl-substituted anthracenederivative represented by the following formula (2) functions as a hostmaterial.

wherein Ar¹ to Ar⁴ are independently a substituted or unsubstituted arylgroup having 6 to 30 atoms that form a ring (hereinafter referred to asthe “ring carbon atoms”) or a substituted or unsubstituted heteroarylgroup having 5 to 20 atoms that form a ring (hereinafter the “ringatoms”);

X¹ to X⁸ are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asilyl group which is substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms and/or a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms, or which is unsubstituted,a cyano group, an alkoxy group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, a halogen atom or a substituted or unsubstitutedhalogenated alkyl group having 1 to 20 carbon atoms;

R¹ to R⁸ are independently a hydrogen atom, a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms, a substitutedor unsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, asilyl group which is substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms and/or a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms, or which is unsubstituted,a cyano group, a substituted or unsubstituted alkoxy group having 1 to20 carbon atoms, a substituted or unsubstituted aryloxy group having 6to 30 ring carbon atom or a substituted or unsubstituted aralkyl grouphaving 6 to 30 ring carbon atoms, and

R¹ and R², R² and R³, R³ and R⁴, R⁵ and R⁶, R⁶ and R⁷ and R⁷ and R⁸ maybe bonded with each other to form a substituted or unsubstitutedhydrocarbon ring or a substituted or unsubstituted heterocyclic ring.

wherein Ar¹¹ is a substituted or unsubstituted arylene group (aromatichydrocarbon group) having 6 to 30 ring carbon atoms or a substituted orunsubstituted heteroarylene group (aromatic heterocyclic group) having 5to 20 ring atoms,

m is an integer of 0 to 3, and when m is 0, Ar¹¹ is a single bond,

Ar¹² is a substituted or unsubstituted aryl group having 6 to 30 ringcarbon atoms or a substituted or unsubstituted heteroaryl group having 5to 20 ring atoms,

n is an integer of 1 to 3; and

when m or n is 2 or more, plural Ar¹¹s and Ar¹²s may be the same ordifferent.

Hereinbelow, each substituent in the formulas (1) and (2) will beexplained with reference to the specific examples, or the like.

In this specification, the “carbon atoms that form a ring” means carbonatoms that constitute a saturated aliphatic cyclic structure, anunsaturated aliphatic cyclic structure or an aromatic hydrocarbon cyclicstructure which are each composed of carbon and hydrogen. The “atomsthat form a ring” means carbon atoms and hetero atoms that constitute asaturated aliphatic cyclic structure, an unsaturated aliphatic cyclicstructure and an aromatic heterocyclic structure each containing ahetero atom.

The “hydrocarbon ring” includes a saturated aliphatic cyclic structure,an unsaturated aliphatic cyclic structure or an aromatic hydrocarboncyclic structure which are each composed of carbon and hydrogen, and the“heterocyclic ring” includes a saturated aliphatic cyclic structure, anunsaturated aliphatic cyclic structure and an aromatic heterocyclicstructure each containing a hetero atom.

In this specification, all atoms constituting the pyrene derivativerepresented by the formula (1) and the phenyl-substituted anthracenederivative represented by the formula (2) include correspondingisotopes.

The aryl group having 6 to 30 ring carbon atoms represented by Ar¹ toAr⁴, X¹ to X⁸ and R¹ to R⁸ and Ar¹² includes a non-fused aromatichydrocarbon ring group having 6 to 30 ring carbon atoms, a fusedaromatic hydrocarbon ring group having 10 to 30 ring carbon atoms and aring-assembling aromatic hydrocarbon ring group having 9 to 30 ringcarbon atoms. Here, the “non-fused aromatic hydrocarbon ring group”means a group in which a plurality of aromatic rings (a monocyclic ringand/or a fused ring) is bonded by a single bond. The “fused aromatichydrocarbon ring group” means a ring in which a plurality of aromaticrings are bonded by two or more common ring carbon atoms. The“ring-assembling aromatic hydrocarbon ring group” means a ring in whichan aromatic ring and an aliphatic ring are bonded by two or more commoncarbon ring atoms.

Specific examples of the aryl group having 6 to 30 ring carbon atomsinclude a phenyl group, a naphthyl group, an anthryl group, aphenanthryl group, a naphthacenyl group, a pyrenyl group, a crysenylgroup, a fluorenyl group, a benzo[c]phenanthryl group, abenzo[g]chrysenyl group, a triphenylenyl group, a 9,9-dimethylfluorenylgroup, a benzofluorenyl group, a dibenzofluorenyl group, a biphenylylgroup, a terphenylyl group and a fluoranthenyl group. Of theabove-mentioned aryl groups, a phenyl group, a biphenylyl group, a tolylgroup, a xylyl group and a naphthyl group are particularly preferable.It is preferred that the aryl group have 6 to 18 ring carbon atoms, morepreferably 6 to 10 ring carbon atoms.

The heteroaryl group having 5 to 20 ring atoms represented by Ar¹ to Ar⁴and Ar¹² includes, a non-fused aromatic heterocyclic group having 5 to20 ring atoms, and a fused aromatic heterocyclic group having 10 to 20ring atoms and a ring-assembling aromatic heterocyclic group having 9 to20 ring atoms. Here, the “non-fused aromatic heterocyclic group” means agroup in which two or more aromatic rings including one or more aromaticheterocyclic rings (a monocyclic ring and/or a fused ring) are bonded bya single bond. The “fused aromatic heterocyclic group” means a ring inwhich two or more aromatic rings including one or more aromaticheterocyclic rings are bonded by two or more common ring atoms. The“ring-assembling aromatic heterocyclic group” means a ring in which oneor more aromatic rings and one or more aliphatic rings are bonded by twoor more common carbon atoms.

Specific examples of the heteroaryl group having 5 to 20 ring atomsinclude a pyrrolyl group, a pyrazinyl group, a pyridinyl group, anindolyl group, an isoindolyl group, a furyl group, a benzofuranyl group,an isobenzofuranyl group, a dibenzofuranyl group, a dibenzothiophenylgroup, a quinolyl group, an isoquinolyl group, a quinoxalynyl group, acarbazolyl group, a phenanthrydinyl group, an acridinyl group, aphenanthronyl group, a phenazinyl group, a phenothiazinyl group, aphenoxazinyl group, an oxazolyl group, an oxadiazolyl group, a frazanylgroup, a thienyl group, a 2-methylpyrrolyl group, a triazinyl group, apyrimidinyl group or the like. Of these, a dibenzofuranyl group, adibenzothiophenyl group and a carbazolyl group are preferable. It ispreferred that the heteroaryl group have 5 to 14 ring atoms.

As the alkyl group having 1 to 20 carbon atoms represented by X¹ to X⁸and R¹ to R⁸, a methyl group, an ethyl group, a propyl group, anisopropyl group, an n-butyl group, an s-butyl group, an isobutyl group,a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group,an n-octyl group or the like can be given. Of these, a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, ans-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group andan n-hexyl group are preferable. The number of carbon atoms ispreferably 1 to 10, more preferably 1 to 8, with 1 to 6 being furtherpreferable.

As the cycloalkyl group having 3 to 20 ring carbon atoms represented byX¹ to X⁸ and R¹ to R⁸, a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a 1-adamantyl group, a2-adamantyl group, a 1-norbornyl group, a 2-norbornyl group or the likecan be given. The number of ring carbon atoms is preferably 3 to 10,more preferably 3 to 8, with 3 to 6 being further preferable.

As the silyl group substituted by a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms and/or a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms or unsubstituted representedby X¹ to X⁸ and R¹ to R⁸, the following can be given.

The alkyl-substituted sily group is represented by —SiY₃, and examplesof Y include the examples of the alkyl group having 1 to 20 carbonatoms. Specific examples include a trimethylsilyl group, a triethylsilylgroup, a t-butyldimethylsilyl group, a propyldimethylsilyl group or thelike can be given.

The aryl-substituted silyl group is represented by —SiZ₃, and examplesof Z include aryl groups having 6 to 18 ring carbon atoms of theabove-mentioned examples of the aryl groups having 6 to 30 ring carbonatoms. Specific examples include a triphenylsilyl group, aphenydimethylsilyl group, a t-butyldiphenylsilyl group, a tritolylsilylgroup, a trixylylsilyl group or the like can be given.

The alkyl- and aryl-substituted silyl group is represented by—SiY_(n)Z_((3-n)) (n is 1 or 2). As examples of Y, the above examples ofthe alkyl group having 1 to 20 carbon atoms can be given. As examples ofZ, of the above examples of the aryl group having 6 to 30 ring carbonatoms, aryl groups having 6 to 18 ring carbon atoms can be given.

The alkoxy group having 1 to 20 carbon atoms represented by X¹ to X⁸ andR¹ to R⁸ is represented by —OY. Examples of Y include examples of thealkyl group having 1 to 20 carbon atoms. Specific examples include amethoxy group, an ethoxy group, a butoxy group or the like.

The aryloxy group having 6 to 30 ring carbon atoms represented by X¹ toX⁸ and R¹ to R⁸ is represented by —OZ, and examples of Z include theabove-mentioned examples of the aryl group having 6 to 30 ring carbonatoms. Specific examples include a phenoxy group or the like.

The aralkyl group having 6 to 30 ring carbon atoms represented by X¹ toX⁸ and R¹ to R⁸ is represented by —Y—Z, and examples of Y includeexamples of the alkylene group corresponding to the above-mentionedexamples of the alkyl group having 1 to 20 carbon atoms. As examples ofZ, the above-mentioned examples of the aryl group having 6 to 30 ringcarbon atoms can be given. Specific examples include a benzyl group, aphenylethyl group, a 2-phenylpropane-2-yl group or the like can begiven.

As the halogen atom represented by X¹ to X⁸, fluorine, chlorine,bromine, iodine or the like can be given. A fluorine atom is preferable.

As the halogenated alkyl group having 1 to 20 carbon atoms representedby X¹ to X⁸, fluoroalkyl having 1 to 20 carbon atoms is preferable.Specifically, a fluoromethyl group, a difluoromethyl group, atrifluoromethyl group, a fluoroethyl group, a trifluoromethylmethylgroup or the like can be given.

The arylene group having 6 to 30 ring carbon atoms represented by Ar¹¹is represented by —Z—, and as examples of Z, the arylene groupcorresponding to the above-mentioned examples of the aryl group having 6to 30 ring carbon atoms can be given.

The heteroarylene group having 5 to 20 ring atoms represented by Ar¹¹ isrepresented by —P—, and as examples of P, a heteroarylene groupcorresponding to the above-mentioned examples of the heteroaryl grouphaving 5 to 20 ring atoms can be given.

As the substituent of the above-mentioned each “substituted orunsubstituted” group, an alkyl group having 1 to 20 carbon atoms, asilyl group substituted by an alkyl group having 1 to 20 carbon atomsand/or an aryl group having 6 to 18 ring carbon atoms, an alkoxy grouphaving 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbonatoms, a haloalkoxy group having 1 to 20 carbon atoms, an aryl grouphaving 6 to 30 ring carbon atoms, a heteroaryl group having 5 to 20 ringatoms, an aryloxy group having 6 to 30 ring carbon atoms, an aralkylgroup having 6 to 30 ring carbon atoms, a cycloalkyl group having 3 to20 carbon atoms, a cyano group, a carboxy group, a carbonyl compoundhaving 1 to 20 carbon atoms, a fluorine atom, a halogenated alkyl having1 to 20 carbon atoms or the like can be given.

In the above formula (1), R¹ and R², R² and R³, R³ and R⁴, R⁵ and R⁶, R⁶and R⁷, R⁷ and R⁸ may be bonded with each other to form a substituted orunsubstituted hydrocarbon ring or a substituted or unsubstitutedheterocyclic ring. Specific hydrocarbon rings include a naphthyl group,a phenanthryl group, a pyrenyl group, a 9,9-dimethylfluorenyl group orthe like. Specific examples of the formed heterocyclic ring include abenzofuranyl group, a dibenzofuranyl group, a benzothienyl group, adibenzothienyl group, a 1-arylindolyl group, a 9-arylcarbazolyl group orthe like can be given.

In the formula (2), m is a repeating number of Ar¹¹, which is an integerof 0 to 3, preferably 0 to 2. When m is 2 or more, plural Ar¹¹s may bethe same or different. If m is 0, Ar¹¹ is a single bond.

In the formula (2), when m is 1 to 3, n is the number of substitution ofAr¹² to Ar¹¹, which is an integer of 1 to 3, preferably an integer of 1to 2. When n is 2 or more, plural Ar¹²s may be the same or different.When m is 0, n is 1, and Ar¹² is bonded to the anthracene skeleton.

It is preferred that, in the formula (1), X² be a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, a silylgroup which is substituted by a substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms and/or a substituted or unsubstituted arylgroup having 6 to 18 ring carbon atoms, or unsubstituted, or asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms; and X¹ and X³ to X⁸ are hydrogen atoms.

In another preferred embodiment, in the formula (1), X² and X⁶ are asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 10 ring carbonatoms, a silyl group which is substituted by a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms and/or asubstituted or unsubstituted aryl group having 6 to 18 ring carbonatoms, or which is unsubstituted, or a substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, and X¹, X³, X⁴, X⁵, X⁷ and X⁸are hydrogen atoms.

The substituted or unsubstituted alkyl group having 1 to 20 carbon atomsrepresented by X² and X⁶ is preferably an alkyl group having 1 to 6carbon atoms. The silyl group substituted by a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms and/or substitutedor unsubstituted aryl group having 6 to 18 ring carbon atoms representedby X² and X⁶, or unsubstituted is preferably a substituted orunsubstituted alkylsilyl group having 3 to 20 carbon atoms, and morepreferably an alkylsilyl group having 3 to 12 carbon atoms.

In another preferable embodiment, in the formula (1), X¹ to X⁸ arehydrogen atoms.

In the formula (1), it is preferred that X² and X⁶ be a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, a substitutedor unsubstituted alkyl group having 1 to 20 carbon atoms or asubstituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, and X¹, X³ to X⁵ and X⁷ and X⁸ are hydrogen atoms.

It is preferred that, in the formula (1), Ar³ and Ar⁴ are a substitutedor unsubstituted aryl group having 6 to 30 ring carbon atoms.

It is preferred that, in the formula (1), R³ and R⁷, or R² and R⁶, be asubstituted or unsubstituted aryl group having 6 to 30 ring carbonatoms. In this case, it is preferred that the remaining R¹ to R⁸ arehydrogen.

It is preferred that, in the formula (1), Ar³ and Ar⁴ be a substitutedor unsubstituted phenyl group.

In the formula (1), it is preferred that R³ and R⁷ or R² and R⁶ be asubstituted or unsubstituted phenyl group. In this case, it is preferredthat the remaining R¹ to R⁸ are hydrogen.

From the viewpoint of easiness in synthesis, in the formula (1), it ispreferred that at least one or more, more preferably all of Ar¹ and Ar²,Ar³ and Ar⁴, R¹ and R⁵, R² and R⁶, R³ and R⁷, R⁴ and R⁸, X¹ and X⁵, X²and X⁶, X³ and X⁷ and X⁴ and X⁸ be the same (point symmetrical).

It is preferred that, in the formula (2), m be 1 and n be 1.

In this case, it is preferred that Ar¹¹ be a substituted orunsubstituted arylene group having 6 to 18 ring carbon atoms or asubstituted or unsubstituted heteroarylene group having 5 to 20 ringatoms, and Ar¹² be a substituted or unsubstituted aryl group having 6 to18 ring carbon atoms or a substituted or unsubstituted heteroaryl grouphaving 5 to 20 ring atoms.

It is more preferred that Ar¹¹ be a substituted or unsubstitutedphenylene group or a substituted or unsubstituted naphthalene group.

It is further preferred that Ar¹¹ be a substituted or unsubstitutedphenylene group and Ar¹² be a substituted or unsubstituted naphthylgroup.

In the formula (2), it is preferred that m be 0 and n be 1.

In this case, it is preferred that Ar¹² be a substituted orunsubstituted aryl group having 6 to 18 ring carbon atoms or asubstituted or unsubstituted heteroaryl group having 5 to 20 ring atoms.

Further, it is more preferred that Ar¹² be a substituted orunsubstituted naphthyl group, a substituted or unsubstitutedbenzanthracenyl group, a substituted or unsubstituted benzophenanthrenylgroup, a substituted or unsubstituted phenanthryl group or a substitutedor unsubstituted dibenzofuranyl group.

Specific preferable compounds of the pyrene derivative represented bythe formula (1) used in the organic light-emitting medium of theinvention are given below.

The invention further provides the compound represented by the followingformula (10). In the organic light-emitting medium, together with thederivative of the formula (2), the compound represented by the formula(10) can be used. In this case, the derivative represented by theformula (2) and the compound represented by the formula (10) function asthe host material and the dopant material, respectively.

In the formula (10), Ar¹ to Ar⁴ and X¹ to X⁸ are the same as Ar¹ to Ar⁴and X¹ to X⁸ in the formula (1), respectively, and an explanationthereof is omitted. Ar⁵ and Ar⁶ are the same as Ar¹ to Ar⁴ in theformula (1), and an explanation thereof is omitted.

R¹¹, R¹², R¹⁴ to R¹⁶ and R¹⁸ are independently a hydrogen atom, asubstituted or unsubstituted alkyl group having 1 to 20 carbon atoms, asubstituted or unsubstituted cycloalkyl group having 3 to 20 ring carbonatoms, a silyl group which is substituted by a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms and/or asubstituted or unsubstituted aryl group having 6 to 18 ring carbonatoms, or which is unsubstituted, or a substituted or unsubstitutedaralkyl group having 6 to 30 ring carbon atoms.

The alkyl group having 1 to 20 carbon atoms, the cycloalkyl group having3 to 20 ring carbon atoms, the silyl group which is substituted by asubstituted or unsubstituted alkyl group having 1 to 20 carbon atomsand/or a substituted or unsubstituted aryl group having 6 to 18 ringcarbon atoms, or which is unsubstituted, or a substituted orunsubstituted aralkyl group having 6 to 30 ring carbon atoms representedby R¹¹, R¹², R¹⁴ to R¹⁶ and R¹⁸, and the substituents substituting thesegroups are respectively the same as the corresponding groups in theformula (1) and the substituents thereof, and an explanation thereof isomitted.

In the explanation of preferred examples of the derivative in theformula (1), the explanation for Ar¹ to Ar⁴ and X¹ to X⁸ also applies tothe derivatives of the formula (10).

It is preferred that Ar⁵ and Ar⁶ be a substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, with a substituted orunsubstituted phenyl group being more preferable.

As for R¹¹, R¹², R¹⁴ to R¹⁶ and R¹⁸, they are preferably hydrogen.

Further, it is preferred that R¹² and R¹⁶ be a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms, with asubstituted or unsubstituted phenyl group being more preferable. In thiscase, the remaining R¹¹, R¹², R¹⁴ to R¹⁶ and R¹⁸ are hydrogen.

The compound represented by the formula (10) in which Ar⁵ and Ar⁶(phenyl, in particular) are bonded to the m-position has a smallbroadening of the conjugated system relative to the amine part ascompared with the compound in which Ar⁵ and Ar⁶ are bonded to thep-position. In addition, the electron donating property to the aminepart is suppressed, and hence, this compound tends to have a shorterwavelength. As a result, color purity is improved. Further, in themolecular structure, flatness is improved three-dimensionally, wherebyenergy transfer with a host atom is conducted efficiently, resulting intendency of improvement in efficiency.

Specific preferable compounds of the phenyl-substituted anthracenederivative represented by the formula (2) used in the organic emissionmedium of the invention are shown below.

An organic light-emitting medium in which at least one of the pyrenederivatives represented by the above formula (1) is used as a dopingmaterial (dopant) and at least one of the phenyl-substituted anthracenederivatives represented by the above formula (2) is used as a hostmaterial has a high luminous efficiency and has a long lifetime. Byusing this light-emitting medium as an emitting layer of an organicelectroluminescence device or the like, a device having a high luminousefficiency and a long life can be obtained.

In the organic light-emitting medium of the invention, in order to allowit to be a light-emitting medium having a high luminous efficiency and along lifetime without impairing the advantageous effects, in addition tothe above-mentioned pyrene derivative and the phenyl-substitutedanthracene derivative, various materials may be contained. As for thematerials which can be contained, an explanation will be made later inthe explanation of the organic electroluminescence device of theinvention, given later.

II. Organic Electroluminescence Device

In the organic electroluminescence device of the invention (hereinafterreferred to as the organic EL device of the invention), one or moreorganic thin films including an emitting layer are disposed between ananode and a cathode.

The emitting layer includes the organic light-emitting medium of theinvention or the pyrene derivative represented by the formula (10). Ifthe emitting layer includes the pyrene derivative represented by theformula (10), it is preferred that the derivative of the formula (2) becontained as a host together.

In the organic EL device of the invention, the emitting layer comprisesa host material and a doping material if it is an organic layer havingan emitting function and has a doping system. At this time, the hostmaterial mainly promotes re-combination of electrons and holes and has afunction of confining excitons in the emitting layer. The dopantmaterial has a function of allowing the excitons obtained byre-combination to emit light efficiently.

Easiness in injecting of holes and electrons to the emitting layer maydiffer. Further, the hole-transporting capability and theelectron-transporting capability which are shown by the mobility ofholes and electrons in the emitting layer may differ.

As the method for forming an organic thin film layer, a known methodsuch as a vapor deposition method, a spin coating method and an LBmethod can be used. An organic thin film layer can be formed by a methodin which a binder such as a resin and a material compound are dissolvedin a solvent to obtain a solution, and this solution is formed into athin film by a spin coating method or the like.

If a plurality of organic thin film layers is formed, they may be formedby the same method or by two or two or more methods.

In the invention, as an organic EL device having a plurality of organicthin film layers, the following stacked structures can be given.

(anode/hole-injecting layer/emitting layer/cathode), (anode/emittinglayer/electron-injecting layer/cathode), (anode/hole-injectinglayer/emitting layer/electron-injecting layer/cathode),(anode/hole-injecting layer/hole-transporting layer/emittinglayer/electron-injecting layer/cathode), (anode/hole-injectinglayer/hole-transporting layer/emitting layer/electron-transportinglayer/electron-injecting layer/cathode), etc.

The organic EL device of the invention may have a tandem devicestructure in which at least two emitting layers are provided. Specificexamples of the device structure are shown below.

Anode/first emitting layer/intermediate layer/second emittinglayer/electron-transporting region/cathode Anode/first emittinglayer/electron-transporting region/intermediate layer/second emittinglayer/cathode Anode/first emitting layer/electron-transportingregion/intermediate layer/second emitting layer/electron-transportingregion/cathodeAnode/first emitting layer/intermediate layer/second emittinglayer/electron-transporting region/cathode Anode/first emittinglayer/electron-transporting region/intermediate layer/second emittinglayer/cathode Anode/first emitting layer/carrier-blocking layer/secondemitting layer/electron-transporting region/cathode Anode/first emittinglayer/carrier-blocking layer/second emitting layer/third emittinglayer/electron-transporting region/cathode

The organic light-emitting medium of the invention or the pyrenederivative of the formula (10) can be used in one or two or more ofthese emitting layers. Further, for other emitting layers, an organiclight-emitting medium using other fluorescent materials or an organiclight-emitting medium using phosphorescent materials can be used.

By allowing an organic thin film layer to be formed of a plurality oflayers, an organic EL device can be prevented from lowering in luminanceor lifetime by quenching. A hole-injecting layer, an emitting layer andan electron-injecting layer may respectively be formed of two or morelayers. In this case, in the case of a hole-injecting layer, a layer forinjecting holes from an electrode is called a hole-injecting layer, anda layer which receives holes from the hole-injecting layer andtransports to the emitting layer is called a hole-transporting layer.Similarly, in the case of an electron-injecting layer, a layer forinjecting electrons from an electrode is called an electron-injectinglayer and a layer for receiving electrons from an electron-injectinglayer and transporting electrons to an emitting layer is called anelectron-transporting layer. Each of these layers is selected for use inview of the factors such as the energy level of the material, the heatresistance, adhesion with an organic layer or a metal electrode or thelike.

As the material which can be used in the emitting layer which does notuse the organic emitting medium of the invention or the pyrenederivative of the formula (10), fused polycyclic aromatic compounds suchas naphthalene, phenanthrene, rubrene, anthracene, tetracene, pyrene,perylene, chrysene, decacyclene, coronene, tetraphenylcyclopentadiene,pentaphenylcyclopentadiene, fluorene, spirofluorene and derivativesthereof, organic metal complexes such as tris(8-quinolinolate)aluminum,triarylamine derivatives, styrylamine derivatives, stilbene derivatives,coumarin derivatives, pyrane derivatives, oxazone derivatives,benzothiazole derivatives, benzoxazole derivatives, benzimidazolederivatives, pyrazine derivatives, cinnamate derivatives,diketo-pyrrolo-pyrrole derivatives, acrylidone derivatives andquinacrylidone derivatives can be used, for example.

The above-mentioned compounds can be used in the emitting layer whichuses the organic light-emitting medium of the invention or the pyrenederivative represented by the formula (10) as long as it does not impairattaining the object of the invention.

As the hole-injecting material, a compound which can transport holes,exhibits hole-injecting effect from the anode and excellenthole-injection effect for the emitting layer or the emitting material,and has an excellent capability of forming a thin film is preferable.Specific examples thereof include, though not limited thereto,phthalocyanine derivatives, naphthalocyanine derivatives, porphylinederivatives, benzidine-type triphenylamine, diamine-type triphenylamine,hexacyanohexaazatriphenylene, derivatives thereof, and polymer materialssuch as polyvinylcarbazole, polysilane and conductive polymers.

Of the hole-injecting materials usable in the organic EL device of theinvention, further effective hole-injecting materials are phthalocyaninederivatives.

Examples of the phthalocyanine (Pc) derivative include, though notlimited thereto, phthalocyanine derivatives such as H₂Pc, CuPc, CoPc,NiPc, ZnPc, PdPc, FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl₂SiPc,(HO)AlPc, (HO)GaPc, VOPc, TiOPc, MoOPc and GaPc-O-GaPc, andnaphthalocyanine derivatives.

In addition, it is also possible to sensitize carriers by adding to thehole-injecting material an electron-accepting substance such as a TCNQderivative.

Preferable hole-transporting materials usable in the organic EL deviceof the invention are aromatic tertiary amine derivatives.

Examples of the aromatic tertiary amine derivative include, though notlimited thereto,N,N′-diphenyl-N,N′-dinaphthyl-1,1′-biphenyl-4,4′-diamine,N,N,N′,N′-tetrabiphenyl-1,1′-biphenyl-4,4′-diamine or an oligomer or apolymer having these aromatic tertiary amine skeletons.

As the electron-injecting material, a compound which can transportelectrons, exhibits electron-injecting effect from the cathode andexcellent electron-injection effect for the emitting layer or theemitting material, and has an excellent capability of forming a thinfilm is preferable.

In the organic EL device of the invention, further effectiveelectron-injecting materials are a metal complex compound and anitrogen-containing heterocyclic derivative.

Examples of the metal complex compound include, though not limitedthereto, 8-hydroxyquinolinate lithium, bis(8-hydroxyquinolinate)zinc,tris(8-hydroxyquinolinate)aluminum, tris(8-hydroxyquinolinate)gallium,bis(10-hydroxybenzo[h]quinolinate)beryllium andbis(10-hydroxybenzo[h]quinolinate)zinc.

As examples of the nitrogen-containing heterocyclic derivative, oxazole,thiazole, oxadiazole, thiadiazole, triazole, pyridine, pyrimidine,triazine, phenanthroline, benzimidazole, imidazopyridine or the like arepreferable, for example. Of these, a benzimidazole derivative, aphenanthroline derivative and an imidazopyridine derivative arepreferable.

As a preferred embodiment, a dopant is further contained in theseelectron-injecting materials, and in order to facilitate receivingelectrons from the cathode, it is further preferable to dope thevicinity of the cathode interface of the second organic layer with adopant, the representative example of which is an alkali metal.

As the dopant, a donating metal, a donating metal compound and adonating metal complex can be given. These reducing dopants may be usedsingly or in combination of two or more.

In addition, for improving stability of the organic EL device obtainedby the invention to temperature, humidity, atmosphere, etc. it is alsopossible to prepare a protective layer on the surface of the device, andit is also possible to protect the entire device by applying siliconeoil, resin, etc.

As the conductive material used in the anode of the organic EL device ofthe invention, a conductive material having a work function of more than4 eV is suitable. Carbon, aluminum, vanadium, iron, cobalt, nickel,tungsten, silver, gold, platinum, palladium or the like, alloys thereof,oxidized metals which may be used in an ITO substrate and a NESAsubstrate such as tin oxide and indium oxide and organic conductiveresins such as polythiophene and polypyrrole are used.

As the conductive material used in the cathode, a conductive materialhaving a work function of smaller than 4 eV is suitable. Magnesium,calcium, tin, lead, titanium, yttrium, lithium, ruthenium, manganese,aluminum, and lithium fluoride or the like, and alloys thereof are used,but not limited thereto. Representative examples of the alloys include,though not limited thereto, magnesium/silver alloys, magnesium/indiumalloys and lithium/aluminum alloys. The amount ratio of the alloy iscontrolled by the temperature of the deposition source, atmosphere,vacuum degree or the like, and an appropriate ratio is selected. Ifnecessary, the anode and the cathode each may be composed of two or morelayers.

In the organic EL device of the invention, in order to allow it to emitlight efficiently, it is preferred that at least one of the surfaces befully transparent in the emission wavelength region of the device. Inaddition, it is preferred that the substrate also be transparent. Thetransparent electrode is formed such that predetermined transparency canbe ensured by a method such as deposition or sputtering by using theabove-mentioned conductive materials. It is preferred that the electrodeon the emitting surface have a light transmittance of 10% or more.Although no specific restrictions are imposed on the substrate as longas it has mechanical and thermal strength and transparency, a glasssubstrate and a transparent resin film can be given.

Each layer of the organic EL device of the invention can be formed by adry film-forming method such as vacuum vapor deposition, sputtering,plasma coating, ion plating or the like or a wet film-forming methodsuch as spin coating, dipping, flow coating or the like. Although thefilm thickness is not particularly limited, it is required to adjust thefilm thickness to an appropriate value. If the film thickness is toolarge, a large voltage is required to be applied in order to obtain acertain optical output, which results in a poor efficiency. If the filmthickness is too small, pinholes or the like are generated, and asufficient luminance cannot be obtained even if an electrical field isapplied. The suitable film thickness is normally 5 nm to 10 μm, with arange of 10 nm to 0.2 μm being further preferable.

In the case of the wet film-forming method, a thin film is formed bydissolving or dispersing materials forming each layer in an appropriatesolvent such as ethanol, chloroform, tetrahydrofuran and dioxane. Any ofthe above-mentioned solvents can be used.

As the solvent suited to such a wet film-forming method, a solutioncontaining the pyrene derivative of formula (1) and phenyl-substitutedanthracene of the formula (2) as an organic EL material and a solventcan be used.

In each organic thin film layer, an appropriate resin or additive may beused in order to improve film-forming properties, to prevent generationof pinholes in the film, or for other purposes.

EXAMPLES

Hereinbelow, the invention will be described in more detail withreference to the following examples which should not be construed aslimiting the scope of the invention.

Synthesis Example 1 Synthesis of Compound D-1

Compound D-1 was synthesized according to the following scheme.

(a) Synthesis of 2,5-diphenylaniline

Under an argon atmosphere, a mixture of 2,5-dibromoaniline (150 g, 0.598mol), phenylboronic acid (160 g, 1.79 mol),tetrakis(triphenylphosphine)palladium (0) (27.6 g, 0.0234 mol), a 2Maqueous sodium carbonate solution (900 mL, 1.80 mol) and1,2-dimethoxyethane (3.5 L) was stirred at 75° C. for 23 hours. Thereaction mixture was cooled to the room temperature. Then, water wasadded, and precipitated solids were collected by filtration. Theresulting solids were purified by silica gel column chromatography,whereby 119 g (81%) of an intended 2,5-diphenylaniline was obtained.

(b) Synthesis of N-phenyl-2,5-diphenylaniline

A mixture of bromobenzene (36.4 g, 232 mmol), 2,5-diphenylaniline (114g, 464 mmol), synthesized in (a) palladium acetate (II) (1.56 g, 6.96mmol), 8.67 g (13.9 mmol) of BINAP(2,2′-bis(diphenylphosphino)-1,1′-binaphthyl racemic body and 1.5 L oftoluene were heated to 90° C. under an argon atmosphere. Then, sodiumtert-butoxide (44.6 g, 464 mmol) was added, and the resulting mixturewas stirred at 105° C. for 5 hours under an argon atmosphere. Thereaction mixture was cooled to room temperature, and water was added toallow the mixture to separate into two liquids. The solvent of theresulting organic layer was concentrated by reducing pressure, and thethus obtained solids were purified by silica gel chromatography, whereby66.6 g (yield: 85%) of an intended N-phenyl-2,5-diphenylaniline wasobtained.

(c) Synthesis of Compound D-1

A mixture of 1,6-dibromopyrene (23.2 g, 64.5 mmol),N-phenyl-2,5-diphenylaniline (45.6 g, 142 mmol) synthesized in (b),palladium acetate (0.6 g, 2.67 mmol), tri-tert-butylphosphine (1.08 g,5.33 mmol) and toluene (700 ml) was heated to 90° C. under an argonatmosphere. Then, sodium tert-butoxide (15.4 g, 160 mmol) was added, andstirred at 105° C. for 3 hours under an argon atmosphere. The reactionmixture was cooled to room temperature, the purified solids werecollected by filtration. The thus obtained solids were purified bysilica gel chromatography, then purified by re-crystallization, whereby33.7 g (yield: 62%) of an intended compound D-1 was obtained.

As a result of mass spectrometry, the resulting compound was identifiedas the compound D-1 (m/e=840 relative to the molecular weight of840.35).

Example 1

On a glass substrate of 25 mm by 75 mm by 1.1 mm thick, a transparentelectrode of an indium tin oxide was formed into a thickness of 120 nm.This transparent electrode serves as an anode. Subsequently, this glasssubstrate was cleaned by irradiating with UV rays and ozone, and thecleaned glass substrate was mounted in a vacuum deposition apparatus.

On the anode, as a hole-injecting layer, compound HT-1 was deposited ina thickness of 50 nm. On this layer, as a hole-transporting layer,compound HT-2 was deposited in a thickness of 45 nm. Then, an anthracenederivative EM-1 as the host material and the compound D-1 as the dopingmaterial were co-deposited in a mass ratio of 25:5, whereby an emittinglayer with a thickness of 30 nm was formed. On this emitting layer, asan electron-injecting layer, compound ET-1 was deposited in a thicknessof 25 nm. Subsequently, lithium fluoride was deposited in a thickness of1 nm, and then, aluminum was deposited in a thickness of 150 nm, wherebyan organic EL device was fabricated. This aluminum/lithium fluoride filmserves as a cathode.

Compound HT-1, compound HT-2 and compound ET-1 used in the production ofthe organic EL device are compounds having the following structure.

For the resulting organic EL, the device performance (external quantumyield (%)) at the time of deriving at a current density of 10 mA/cm² andthe lifetime (hr) for which the luminance was decreased by 80% from theinitial luminance at a current density of 50 mA/cm² were evaluated. Theresults are shown in Table 1.

The external quantum efficiency (E.Q.E) was measured by the followingmethod.

Current having a current density of 10 mA/cm² was applied to theresulting organic EL device. Emission spectra thereof were measured witha spectroradiometer (CS1000, produced by MINOLTA), and the externalquantum yield was calculated by the following formula.

$\begin{matrix}{{E.Q.E.} = {\frac{N_{P}}{N_{E}} \times 100}} \\{= {\frac{\frac{\left( {\pi/10^{9}} \right){\int{{\varphi (\lambda)} \cdot {\lambda}}}}{hc}}{\frac{J/10}{e}} \times 100}} \\{= {\frac{\frac{\left( {\pi/10^{9}} \right){\sum\left( {{\varphi (\lambda)} \cdot (\lambda)} \right)}}{hc}}{\frac{J/10}{e}} \times 100(\%)}}\end{matrix}$

N_(P): Number of photonsN_(E): Number of electronsπ: Circular constant=3.1416

λ: Wavelength (nm)

φ: Luminescence intensity (W/sr·m²·nm)h: Planck constant=6.63×10⁻³⁴ (J·s)c: Light velocity=3×10⁸ (m/s)J: Current density (mA/cm²)

e: Charge=1.6×10⁻¹⁹ (C) Examples 2 to 15 and Comparative Examples 1 to11

Organic EL devices were fabricated in the same manner as in Example 1,except that the doping materials and the host materials were changed tothe compounds shown in Table 1, and the external quantum yield (%) andthe lifetime (hour) were evaluated. The results are shown in Table 1.

The structural formulas of the compounds used as the doping material andthe host material in the emitting layers of the organic EL devicesproduced in the Examples and the Comparative Examples are shown below.

TABLE 1 Doping Host External quantum Lifetime Examples material materialyield (%) (hr) Example 1 D-1 EM-1 8.6 130 Example 2 D-1 EM-2 8.5 110Example 3 D-1 EM-3 8.5 160 Example 4 D-1 EM-4 9.1 140 Example 5 D-2 EM-28.2 130 Example 6 D-3 EM-1 7.5 100 Example 7 D-3 EM-2 7.8 130 Example 8D-3 EM-3 8.2 100 Example 9 D-4 EM-1 8.3 130 Example 10 D-4 EM-2 8.0 120Example 11 D-5 EM-2 7.9 110 Example 12 D-5 EM-3 7.7 110 Example 13 D-5EM-5 8.2 110 Example 14 D-6 EM-2 8.3 100 Example 15 D-7 EM-1 8.6 100Com. Ex. 1 D-2 H-1 8.2 80 Com. Ex. 2 D-3 H-1 8.2 80 Com. Ex. 3 D-4 H-38.2 60 Com. Ex. 4 D-5 H-2 7.7 65 Com. Ex. 5 D-6 H-1 8.2 45 Com. Ex. 6HD-1 EM-2 7.1 50 Com. Ex. 7 HD-1 H-1 7.5 40 Com. Ex. 8 HD-1 H-2 7.1 50Com. Ex. 9 HD-2 H-2 7.7 30 Com. Ex. 10 HD-3 EM-1 7.7 80 Com. Ex. 11 HD-2EM-1 8.4 30

From the results shown in Table 1, when the pyrene derivativerepresented by the formula (1) was used as a doping material and thephenyl-substituted anthracene derivative represented by the formula (2was used as a host material, a high external quantum yield (%) and along lifetime can be attained.

We consider that, in the invention, by using a pyrene derivative havinga specific structure and a phenyl-substituted anthracene derivativehaving a specific structure in combination, carrier balance is improvedand as a result, an organic EL device having a high luminous efficiencyand a long life can be obtained.

INDUSTRIAL APPLICABILITY

The organic light-emitting medium of the invention is effective forproducing a highly efficient and long-lived organic EL device.

The organic EL device of the invention can be suitably used as a planaremitting body such as a flat panel display of a wall-mounted television,for a copier, a printer, a backlight of a liquid crystal display, orinstruments, a display panel, a sign board, and the like.

The organic light-emitting medium of the invention can be used not onlyin an organic EL device, but also in an electrophotographicphotoreceptor, a photoelectric conversion device, a solar cell, an imagesensor or the like.

Although only some exemplary embodiments and/or examples of thisinvention have been described in detail above, those skilled in the artwill readily appreciated that many modifications are possible in theexemplary embodiments and/or examples without materially departing fromthe novel teachings and advantages of this invention. Accordingly, allsuch modifications are intended to be included within the scope of thisinvention.

The contents of the above-described documents are herein incorporated byreference in its entirety.

1. An organic light-emitting medium comprising a pyrene derivativerepresented by the following formula (1) and a phenyl-substitutedanthracene derivative represented by the following formula (2):

wherein Ar¹ to Ar⁴ are independently a substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, or a substituted orunsubstituted heteroaryl group having 5 to 20 ring atoms, X¹ to X⁸ areindependently a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 20 ring carbon atoms, a silyl group whichis substituted by a substituted or unsubstituted alkyl group having 1 to20 carbon atoms and/or a substituted or unsubstituted aryl group having6 to 18 ring carbon atoms, or which is unsubstituted, a cyano group, asubstituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, a halogen atom, or a substituted or unsubstitutedhalogenated alkyl group having 1 to 20 carbon atoms, R¹ to R⁸ areindependently a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 20 ring carbon atoms, a silyl group whichis substituted by a substituted or unsubstituted alkyl group having 1 to20 carbon atoms and/or a substituted or unsubstituted aryl group having6 to 18 ring carbon atoms, or which is unsubstituted, a cyano group, asubstituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, or a substituted or unsubstituted aralkyl group having 6 to 30ring carbon atoms, and R¹ and R², R² and R³, R³ and R⁴, R⁵ and R⁶, R⁶and R⁷, and R⁷ and R⁸ may be bonded to each other to form a substitutedor unsubstituted hydrocarbon ring or a substituted or unsubstitutedheterocyclic ring,

wherein Ar¹¹ is a substituted or unsubstituted arylene group having 6 to30 ring carbon atoms or a substituted or unsubstituted heteroarylenegroup having 5 to 20 ring atoms, m is an integer of 0 to 3, providedthat Ar¹¹ is a single bond when m is 0, Ar¹² is a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms or asubstituted or unsubstituted heteroaryl group having 5 to 20 ring atoms,n is an integer of 1 to 3, and when m or n is 2 or more, plural Ar¹¹sand Ar¹²s may be the same or different.
 2. The organic light-emittingmedium according to claim 1, wherein X¹ to X⁸ are a hydrogen atom. 3.The organic light-emitting medium according to claim 1, wherein X² andX⁶ are a substituted or unsubstituted aryl group having 6 to 30 ringcarbon atoms, a substituted or unsubstituted alkyl group having 1 to 20carbon atoms or a substituted or unsubstituted cycloalkyl group having 3to 20 ring carbon atoms, and X¹, X³ to X⁵, X⁷ and X⁸ are a hydrogenatom.
 4. The organic light-emitting medium according to claim 1, whereinAr³ and Ar⁴ is a substituted or unsubstituted aryl group having 6 to 30ring carbon atoms.
 5. The organic light-emitting medium according toclaim 1, wherein R³ and R⁷, or R² and R⁶ are a substituted orunsubstituted aryl group having 6 to 30 ring carbon atoms.
 6. Theorganic light-emitting medium according to claim 4, wherein Ar³ and Ar⁴are a substituted or unsubstituted phenyl group.
 7. The organiclight-emitting medium according to claim 5, wherein R³ and R⁷, or R² andR⁶ are a substituted or unsubstituted phenyl group.
 8. The organiclight-emitting medium according to claim 1, wherein m is 1 and n is 1.9. The organic light-emitting medium according to claim 1, wherein m is0 and n is
 1. 10. The organic light-emitting medium according to claim8, wherein Ar¹¹ is a substituted or unsubstituted arylene group having 6to 18 ring carbon atoms or a substituted or unsubstituted heteroarylenegroup having 5 to 20 ring atoms, Ar¹² is a substituted or unsubstitutedaryl group having 6 to 18 ring carbon atoms or a substituted orunsubstituted heteroaryl group having 5 to 20 ring atoms.
 11. Theorganic light-emitting medium according to claim 9, wherein Ar¹¹ is asubstituted or unsubstituted aryl group having 6 to 18 ring carbon atomsor a substituted or unsubstituted heteroaryl group having 5 to 20 ringatoms.
 12. The organic light-emitting medium according to claim 10,wherein Ar¹¹ is a substituted or unsubstituted phenylene group or asubstituted or unsubstituted naphthalenylene group.
 13. The organiclight-emitting medium according to claim 11, wherein Ar¹² is asubstituted or unsubstituted naphthyl group, a substituted orunsubstituted benzanthracenyl group, a substituted or unsubstitutedbenzphenanthrenyl group, a substituted or unsubstituted phenanthrylgroup or a substituted or unsubstituted dibenzofuranyl group.
 14. Theorganic light-emitting medium according to claim 12, wherein Ar¹¹ is asubstituted or unsubstituted phenylene group and Ar¹² is a substitutedor unsubstituted naphthyl group.
 15. A pyrene derivative represented bythe following formula (10):

wherein Ar¹ to Ar⁶ are independently a substituted or unsubstituted arylgroup having 6 to 30 ring carbon atoms, or a substituted orunsubstituted heteroaryl group having 5 to 20 ring atoms, X¹ to X⁸ areindependently a hydrogen atom, a substituted or unsubstituted aryl grouphaving 6 to 30 ring carbon atoms, a substituted or unsubstituted alkylgroup having 1 to 20 carbon atoms, a substituted or unsubstitutedcycloalkyl group having 3 to 20 ring carbon atoms, a silyl group whichis substituted by a substituted or unsubstituted alkyl group having 1 to20 carbon atoms and/or a substituted or unsubstituted aryl group having6 to 18 ring carbon atoms, or which is unsubstituted, a cyano group, asubstituted or unsubstituted alkoxy group having 1 to 20 carbon atoms, asubstituted or unsubstituted aryloxy group having 6 to 30 ring carbonatoms, a substituted or unsubstituted aralkyl group having 6 to 30 ringcarbon atoms, a halogen atom, or a substituted or unsubstitutedhalogenated alkyl group having 1 to 20 carbon atoms, R¹¹, R¹², R¹⁴ toR¹⁶ and R¹⁸ are independently a hydrogen atom, a substituted orunsubstituted alkyl group having 1 to 20 carbon atoms, a substituted orunsubstituted cycloalkyl group having 3 to 20 ring carbon atoms, a silylgroup which is substituted by a substituted or unsubstituted alkyl grouphaving 1 to 20 carbon atoms and/or a substituted or unsubstituted arylgroup having 6 to 18 ring carbon atoms, or which is unsubstituted, or asubstituted or unsubstituted aralkyl group having 6 to 30 ring carbonatoms.
 16. An organic electroluminescence medium comprising an anode anda cathode, and one or more organic thin film layers including anemitting layer between the anode and the cathode; the emitting layercomprising the organic light-emitting device according to claim
 1. 17.An organic electroluminescence medium comprising an anode and a cathode,and one or more organic thin film layers including an emitting layerbetween the anode and the cathode; the emitting layer comprising thepyrene derivative according to claim 15.